closes openflexure-helpdesk#6

Make build work out of the box on MacOS

OpenSCAD isn't in PATH on MacOS by default - this changes build.py to use the path to which OpenSCAD is installed on MacOS machines.

See merge request !158

Added a taller microscope stand

See merge request !160

(╯°□°）╯︵ ┻━┻

The bridge over the SD card needs to be straight.  This is now
achieved (in my view) quite elegantly with convex hulls, rather than by adding in
material.

There are now two versions of the motor_driver_case, one for the
sangaboard and one for an arduino nano

Updated microscope_stand for parametric wall thickness

See merge request !157

Doesn't seem to be available in sandbox yet.

This reverts commit 8129c1521dc154777ae9b6d7b74b5b07eea91f15.

The fluorescence cutout was shifted downwards only for
the rms_f50d13 optics module, which means the infinity
corrected one breaks.  I've switched it around so that
it's in the lower position by default, and only the f=40mm
version has the higher position.

I changed the wrong line by accident... oops!

In order to use the same epi-illuminator with different cameras/optics,
we need to ensure it's a constant distance from the sensor
(i.e. the image plane).  This should
now be the case.

I now add in the beamsplitter casing properly,
so the cut-out doesn't make holes in the
optics module any more.
Also fixed the height of the cut-out relative to the camera sensor.

Closes #156

Adding the motor order to the documentation

Closes #156

See merge request !165

Zenodo integration

See merge request !152

Fixed fl cutout

See merge request !164

Wall thickness and nano-based motor driver case

See merge request !162

Print page clarity and circular link.

See merge request !166

Add a tip about power supply.

See merge request !169

Added OF emblem to illumination dovetail

See merge request !171

Added letters to the feet.

See merge request !170

Fix: Corrects small typo in 0_bill_of_materials.md

See merge request !167